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Plug-in hybrid electric vehicles produce almost five times greater planet-heating emissions than official figures show, as per a recent analysis.

Widening Gap Between Lab and Actual CO2 Output

Data shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, according to research carried out by a advocacy organization. This differs sharply with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 cars sold in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher participating in the study. “That gap is widening and poses a serious issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to overall mileage. The team found that only 27% of driving was completed in EV mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were significantly higher than official estimates. This happened because EV motors were insufficiently powerful enough to operate independently, leading to engines burning gasoline for nearly one-third of the distance covered in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend about €500 more per year in running costs than is estimated under lab tests.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the mark,” stated a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have lately been drawn again into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car manufacturing.

Some high-level officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the regulation.

One external energy economics expert, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which segments of the automotive industry claimed there was too little data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they stated. “All policy adjustments concerning PHEVs should be implemented with extreme caution and considering this data.”